Synchronous control of clutch servos



May 18, 1937. cF. KETTERING 2,080,487

SYNCHRONOUS CONTROL OF CLUTCH SERVOS May 18, i937. c. F. KETTERING VSYNCHRONOUS CONTROL OF' CLUTCH SERVOS Filed May 28, 1931 2 Sheets-Sheet 2 Patented May 18, 1937 l UNITED STATES.

PATENT OFFICE Charles F.

mesne assignments, poration, Detroit, Delaware VOS Kettering, Dayton, Ohio, assignor, by

to General Motors Cor- Mich., a corporation of Applicata@ May 28, 1931, serial No. 540,654

7 Claims.

This invention relates to motor vehicles. More particularly it relates to control mechanism for motor vehicles wherein power-operated means is used to release the clutch.

The,primary object is to improve the operation of such a power-operated clutch releasing device. A further and more specific object is to improve the action of clutch reengagement.

Other objects and advantages will be understood from the following specification.

The invention will be described with reference to the accompanying drawings, which show several illustrative embodiments.

In the drawings- Fig. 1 is a view of an engine of a motor vehicle, the-novel details associated therewith being shown partly in section.

Fig. 2 is a view partly in side elevation and partly in section of the clutch and transmission units showing a power take-off associated with the lat- Fig. 3 is a transverse sectionthrough a part of the control mechanism employed in a modied form of the invention.

Fig. 4 is a perspective view of the modified control mechanism.

The engine clutch of a motor vehicle is usually controlled by a pedal operated by the drivers foot. It is already well known that power derived from some moving part of the vehicle may be used to disengage the clutch. Air pressure, both above or below atmosphere, pressure from circulating liquids and mechanical interlinkage have been used. The controls for power operation of the clutch have sometimes been connected to levers or pedals aiecting clutch operation only. The controls have also been connected -to pedals orl levers which also aiect other functions on the vehicle. The control on the servo is conveniently connected to the accelerator pedal in sucha way that the clutch is disengaged when the accelerator pedal is in the retracted position. It has been found very difficult to get satisfactory operation under all `conditions of operation with such a control arrangement. If the rate of clutch reengagement is satisfactory for moderate speed driving the clutch may engage on reopening the throttle when the car is free Wheeling at high speed before the engine speed has reached the clutch shaft speed, with the result that the engine momentarily slows down the car.

The present invention provides a simple mechanical means for preventing the clutch reengagement until the engine reaches the clutch shaft speed. It eliminates the need of any advcated in transmission housing toe board 2l is an accelerator pedal 3l which is ditional piping to carry fluids under pressure between various locations on the car other than connections needed for the servo itself. It also eliminates the need of using electrical wiring. contacts or special generators of electrical current. Referring to Fig. 1, numeral 1 engine of a motor vehicle. as provided with a carburetor 9 and an induction pipe I I communicating with an intake manifold I3. At I is a lever pivoted to the induction pipe, the lever operating a throttle valve within the induction pipe.

The position of the engin the car is made clear by Fig. 1 which shows the dash I9, the toe board at 2l, and the oor board at'23. The gear shift lever 25 operates as usual to shift gears shown in part by numeral 21 lo- 29. Pivoted to the represents the in its relation to actuated to its release position by a spring 33.

Theengine is shown A tie-rod connects the pedal 3l to the throttle lever I5. At 31 is the conventional clutch pedal pivoted at`39. This pedal operates to release the clutch. This clutch is located' within the clutch housing 4I. The clutch couples the engine crankshaft 43 to the clutch driven shaft 45. Counter-clockwise rotation of the pedal 31 releases the clutch.

There is provided a power-operated device to release the'clutch and this power-operated device is rendered active incidental tolthe clockwise or release movement of the accelerator pedal 3l. When the operator allows the accelerator pedal to swing up under the inuence of spring 33, he not only cuts olf the flow ofl explosive mixture but incidentally thereto he renders active the clutch-releasing power device. 4-1 is a power cylinder having a cover 49 with one or more air openings as shown at 5I. A diaphragm 53 is clamped between the cylinder and the cover and carries a rod 55 jointed to a rod 51 which latter rod has a sliding connection with the end of a lever 59 carried by the pedal pivot shaft 39. By the provision of nuts 6I at the end of rod 51, a movement of the diaphragm 53 to the left from the position shown in Fig. 1 pulls upon the lever 59 and releases the clutch Ajust as vit may be released by depression ofthe clutch pedal 31. A spring 63 is shown operable to return the lever 59 to its intial position. This connection between rod 51 and lever 59 permits the operation of the clutch by the pedal 31 without pro- The movement of the diaphragm to the left is produced by a pressure differential on the two Y sides of the diaphragm. Pressure on the right side is always atmospheric, owingto the open- 5 ings 5|. Provision is made to reduce the pressure on the left side of the diaphragm. A conduit 65 is connected to the manifold I3 and to one end of a valve member 61. The other end of the valve member has slidable therein a pisl0 ton 69. To this piston is connected a rod 1| terminating in a valve 13 having opposite seats 15 and 11. A spring 19 tends to move the valve 13 to a position away from its seat 11. Apipe 8| connects the chamber in the power cylinder at the left of the diaphragm to the region of the valve member adjacent the valve and between the seats, so that the space in the power cylinder to the left of the diaphragm may be put into communication with the suction pipe 65 when the 20 valve 13 is moved from its seat 11. When the valve 13 is on its seat 11, the pipe 8| connecting the power unit with the valve member 61 cooperates with a pipe 83 and communication is afforded with a control member 85 having an. at-

mospheric opening 81.

A connection is provided between lever I5 and the piston 69 whereby the depression of the accelerator pedal 3| may not only rock lever I5 but also may move the valve 13 to its seat 11 to the end that the left side of the power unit may be vented through passages 8 I, 61, 83, and 85. With the parts in this position the clutch will be engaged by the springs usually provided for the purpose.

Since there must be provided a further throttle opening movement after the valve 13 is seated, the following structure is provided. A rod 89 is pivoted to the piston 69 and secured as by threading to the end of a spring housing 9|. Slidable 40 in the other end of the housing 9| is a head 93 on a rod 95 which is pivoted to an extension arm 91 of lever |5. A spring 99 within the cylinder 9| yieldinglypermits movement of the throttle lever I5 after the valve 13 is seated as will be obvious.

`While the accelerator pedal is in the dotted line position, the valve 13 will be drawn from its seat 11 and seated at 15 so that the engine suction is operable to pull the diaphragm 53 and release the clutch. The parts are so arranged that the first increment of movement-of the pedal 3| downward from its dotted line position will move the valve 13 to its seat 11 withoutv opening the throttle to any considerable extent, not

55 enough to very greatly increase the rate of rotation of the engine shaft. This first increment of movement serves to vent the power cylinder and permit the clutch to engage. Thereafter, and upon further movement of accelerator 3|,

relative movement occurs between head 93-and cylinder 9| and the throttle continues to open.

If the operator now wishes to make a gear change or for any other reason wishes to release the clutch, as for coasting, he may remove his foot from the pedal 3| and the valve 13 shifts from seat 11 to seat 15 and the engine suction causes the clutch to be released. It may be that the operator will wish to use .his engine for a brake, as on a steep hill. In that event he will relieve the pressure on the pedal 3| to an extent suiiicient to partly cut off the supply of fuel, but

not quite. enough to reduce the engine to the idling speed it assumes when his foot is removed from the accelerator. This partial movement will be insufficient to move 13 from` its seat 11 and the clutch will remain engaged so that the engine may be used as a brake. With complete removal of the foot the engine assumes idling speed and the clutch is released.

With a construction as above described, the 5 operation may be somewhat unsatisfactory in one respect. If the operator releases the accelerator 3| the engine shaft 43 quickly comes to its idling speed while the momentum of the car prevents the shaft 45 from correspondingly rel0 ducing its rate of rotation. It may be that the operator will wish to increase the speed of the car before the rate of rotation of the two shafts has become synchronized. In his effort to increase the speed of the car he again depresses the l5 pedal 3| which opens the throttle and vents the power cylinder through opening 81 as has beenl explained. This action would be attended by a prompt reengagement of the clutch. If such reengagement occurs while the shaft 45 is ro- 20 tating faster than shaft 43, the engine momentarily checks the car speed by acting as a brake, an operation which the operator does not wish. This invention provides means to prevent the clutch reengagement under such circumstances 25 until the shaft 43 under the influence of the opening throttle attains the speed of shaft 45.

A iiexible shaft |0| within a exible shaft housing |03 takes its drive from a gear |05 in the gear housing 29. This gear |05 is rotated by one 30 of the gears f the constant mesh train. It is therefore driven in timed relation to shaft 45. Another flexible shaft within shaft housing |01 is driven by gearing |09 associated with the crankshaft 43. 35

A differential device is operated by the two flexible shafts. It comprises a disc rotatable with shaft |0| and a disc ||3 rotatable with the other shaft. 'Ihe discs are yieldingly pressed together by a spring |I5. A cage I|1 is located 40 between the discs. The cage carries a circumferential series of balls II 9 which are received in channels in the discs. The cage has an axial pin |2| on which. is rotatably supported the end of a. rod |23. Rod |23 is pivoted to the end of 45 a rod |25 slidably guided in the end of member 85. This rod |25 has i'ormed'thereon a plunger |21. A closure plug |3I limits the movement of plunger |21 in one direction and a shoulder |33 limits the movement of an enlargement |28 50 on rod |25 in the opposite direction. A spring |35 biases the parts to the positions shown. The shaft |0| is geared so that it rotates at substantially the same rate of rotation as the shaft within housing |01 when the clutch is engaged. The 55 discs are rotating in opposite directions and the balls between the discs are turning with rolling contact with both discs as long as the rotation of the shafts and discs continues at substantially the same rate. The balls will tend to revolve 60 about the center of the discs only if there be inequality inthe rate of rotation of the discs. 'I'here then follows a rotary movement of the cage and its pin 2|. The drawings show the condition where disc III, driven by shaft |03, is 65 rotating at the same rate as disc ||3. The cage I I1 is not revolving. The plunger |21 is engaged with a stop |3| and the power unit is vented by the opening of pipe 83 to the air through the opening 81. With the power cylinder thus vented` 70 the clutch will be engaged by its springs as usual. The operator may then release pressure on accelerator 3|, whereupon the valve 13 moves to close the air vent and open the suction passage. The clutch is thereby opened and the vehicle may u holds the vent open as in Fig. 1.

unequal rotation causes the cage ||1 to rotate until part |29 engages the shoulder |33. The plunger |21 -is thereby moved over the opening 81. If at this time the operator depresses the accelerator to increase the speed of the vehicle, the valve 1,3 cutsoff the suction and if the clutch should be engaged'the relatively slow speed of the engine shaft would serve as a brake on the clutch shaftand check the movement of the i vehicle, but the clutch cannot engage until the vent 81 is opened and this venting cannot occur until the speed of the two discs and H3 is the same, or so nearly the same that the spring |35 may move the plunger |21 to the position shown in the drawings. It will be understood that at starting the clutch is engaged by its conventional springs since there is then no engine suction to effect clutch release. Spring |35, too, At starting, the throttle is partially opened by the pedal 3| or otherwise, thus closing the suction passage between tubes and 8| and thereby providing communication between the power cylinder-and vent opening 81. This condition lpermits the clutch to remain engaged by its springs until such time as the accelerator is released, thereby reestablishing` the suction line and effecting clutch release.

A modified form of control mechanism is shown in Figs. 3 and 4. In the invention shown by these figures pinions are used on the adjacent ends of the shafts', driven by the vengine shaft and clutch shaft. These pinions engage pinions on a carrier like that of a conventional differential, and the rotation of the carrier is made use of to move the plunger |21 as in Fig. 1. Except for this difference the-structure of this modication is the sameas that illustrated by Fig. 1. Referring more particularly -to Figs. 3 and 4, shaft |5| may be the shaft driven by the flexible shaft |0| and shaft- |53 may be the shaft driven .by the flexible shaft |01. These shafts |5| and |53 are journaled in brackets |55 and |51. Within the brackets |55 and |51 is a cage or pinion carrier |53 having diametrically opposed pins |5| lfor rotatably supporting bevel pinions |63 meshing with corresponding pinions |65 secured to the ends of shafts |5| and |53. The pinion carrier is itself rotatably supported on the shafts |5| ,and |53 immediately within the brackets.

Surrounding the carrier |59l and engaging an intermediate frictional face thereof at |55 is a friction band |61. 'I'he upper ends of the brackets have slots |69 and a pin |1| extends through the slots and is fixed in a block |13. One end of the friction band is pivotally anchored to the block as at |15. The other end of the block and the adjacent end of the band have cooperating lugs |11 and |19 separated by a spring I'BI. An adjustable bolt |83 is provided to adjustably connect the block to the end of the band and thereby predetermine the grip of the band on the friction surface |55 of the pinion carrier. The frictional grip should be suicient to cause the band and the block to move with the carrier when unequal rotation occurs until the pin engages the one or the other of the ends of the slots. The block has a lug |83 to which is pivoted the equivalent of the rod |23 of Fig. l, which rod is here represented as |23.

The operation will be readily understood. When the shafts |03 and |01 are rotating at substantially equal speeds, the two pinions |53 are rotating in opposite directions at equal speeds and the carrier is not moving. If the pedal 3| be released, the clutch is automaticallydisengaged by the action of the suction from the manifold.

Then the pinion |65 on shaft. |5| rotates faster than the pinion |65 on shaft |53. The carrier` |59 then rotates and carries the band and the block with it until the end of -the slot engages the pin. As it moves with the brake band, the block pulls on rod |23 and draws the plunger over the opening 81.

If now the operator depresses the accelerator pedal 3| in an effort to speed upthe vehicle, the valve 13 closes the suction conduit, but the vent.- ing of the power cylinder and the. reengagement of the clutch cannot occur until the plunger |21 is moved from over the atmospheric opening 81. This movement cannot take place until the unequal rates of rotation of the two pinions |55 ceases. This stopping of the unequal rotation may occur by a decrease inthe speed of the clutch vor by an increase in the-speed of the engine shaft.

1. \In a motor vehicle, an engine having an engine shaft, a driving shaft, a clutch to couple saidengine shaft and said driving shaft, -yielding means to bias said clutch to engaged position, power means to release said clutch and means rotatable by a difference in rates of rotation of said shafts to prevent clutch engagement.

2. In a motor vehicle, an engine havingan engine shaft, a driving shaft, a clutch to couple said engine shaft and said driving shaft, yielding means to bias said clutch to engaged position, power means to release said clutch and means mounted to have a limited movement of rotation dependent upon a difference in rates of rotation of said shafts to prevent clutch reengagement.

3. In a motor vehicle. an engine having an engine shaft, a driving shaft, a clutch .to couple saldvengine shaft and said driving shaft, yielding means to bias said clutch to engaged position, a first driven shaft rotated by the engine shaft, a seconddriven shaft rotated by the driving shaft, said shafts being geared to have substantially'the same rates of rotation when the said clutch is l movable 'to afford communication between said power unit and said source of suction and also movable to a second position to cut off said suction and vent the power unit, a first driven shaft rotated by the engine shaft, a second driven shaft rotated by the clutch shaft, a cage rotated by said rst a'nd second shafts upon a difference in the rates of rotation of said shafts, means operated by said cage to prevent the venting of said power unit when said rst and second driven shafts are rotating at different rates.

5. In a motor vehicle, in combination, anengine driving an auxiliary shaft rotatable at a predetermined speed ratio, an engine clutch, a clutch shaft, a second auxiliary shaft driven from the l device, linkage connecting the differential means to the control means whereby clutch reengagement is prevented when the clutch shaft speed exceeds the engine speed.

6. In a servo mechanism for the engine clutch l5 of a motor vehicle, inv combination, engine throt-f tle control mechanism, a chamber closed at one end containing a diaphragm, a connection between the diaphragm and the clutch disengaging mechanism, a valve casing having a connection to the intake manifold, a connection to theservo chamber, and a third connection to a second valve casing, a valve in the first valve casing connected to the engine throttle control mechanism so that the servo. chamber is connected to the intake manifold when the throttle is closed, but is connected to the second valve casing whenthe throttle is opened, a valve in the second valve casing which cuts off connection between the interior and the atmosphere in one extreme position of travel and which permits connection between the atmosphere and the first valve casing in the second extreme position of travel, a shaft driven by the engine at a predetermined speed ratio, a second shaft driven by the engine clutch at approximately the same speed ratio as the engine drive to the first shaft, a disc driven by the rst shaft, a second disc mounted coaxially and spaced from the first disc driven from the second shaft in reversed direction to the first disc, a set of balls between the discs in frictional contact with both discs, a spring maintaining a definite pressure between the balls and the discs, a cage engaging the balls to restrain their motion about the axis of the two discs, said cage being capable of a. limited rotary motion about the axis of the discs, a link between the cage andthe second valve arranged so that the valve is moved to the closed position when the clutch shaft turns faster than the engine shaft.

7. In a motor vehicle, an engine having an engine shaft, a driving shaft, a clutch to couple said engine shaft and said driving shaft, a uid power unit having a movable member to release said clutch, a source of suction, a valve movable to afford communication between said power unit and said source of suction and also movablel to a second position to cut ofi.' said suction and vent the power unit, a first driven shaft rotated by the engine shaft, a second driven shaft rotated by the clutch shaft, differential means including gear elements carried by said driven shafts and a carrier having pinions engaging said gears, and means responsive to the rotation of said carrier to prevent the venting of said power cylinder while the first and second driven shafts are rotating at different rates.

CHARLES F. KE'I'I'ERING., 

